Children with diabetic ketoacidosis risk neurological complications such as cerebral edema with high morbidity. To prevent cerebral edema, it is essential to control correction of hypovolemia, hyperglycemia and natremia. Markers usually used in management of diabetic ketoacidosis don't always permit an optimal care.

Plasma copeptin levels reflect vasopressin secretion which is high in diabetic ketoacidosis.

Therefore, monitoring of plasma copeptin levels could be of interest in children with diabetic ketoacidosis and risk of sévère neurological complications.

Biological risk factors for severe complications in diabetic ketoacidosis are described (high blood glucose level, metabolic acidosis, high blood urea nitrogen, hypernatremia) but their dosage and monitoring are not sufficient to distinguish high risks situations.

Several studies suggest that vasopressin secretion is increased in diabetic ketoacidosis. This high level could be important in occurrence of cerebral edema. Monitoring of vasopressin levels could then have an interest in patients at risk of severe complications but reliability of copeptin dosage depend of collection conditions and its packaging. These conditions are difficult to ensure and copeptin dosage, which represent vasopressin secretion, is easier to perform.

Copeptin dosage could then be a new biological marker, more accurate and specific, for an optimal management of diabetic ketoacidosis.

This type of study has never been carried out neither in children nor in adults.

Inclusion criteria:

• Children between 6 months and 16 years
• Diagnosis of diabetes mellitus type 1 (cardinal syndrome, blood glucose level > 7 mmol/L in the fasted state or > 11 mmol/L not in fasted state, no signs for another type of diabetes mellitus)
• Children who need an exclusive intravenous rehydration for 36 hours
• Written informed consent of legal representative and of the child if possible
• Beneficiary of State Social Insurance

Exclusion criteria:

• Child under the age of 6 months or older than 16 years
• Non exclusive intravenous réhydration for at least 36 hours
• Child moved from another institution and for whom an intravenous rehydration or insulin therapy have already begun
• Non type 1 diabetes mellitus
• Non affiliation to State Social Insurance